This invention relates to a synchronous belt in which a tooth part formed on a belt body is covered with a woven fabric, and particularly relates to an improvement of the woven fabric.
A synchronous belt in which a tooth part formed on a belt body is covered with a woven fabric has been used in variable field and, in its turn, has used under sever conditions such as high rotation, high loading, high temperature. Under such conditions, increase in durability thereof is desired since the belt life is shortened because of degradation of the materials of the belt, chip-out of the tooth part and breakage of the tension member in a short period.
In addition, with machine tools for automobiles and home appliance high graded, noise at belt driving is desired to reduce.
In order to enhance the durability of the synchronous belt, it is proposed in Patent Application Laying Open Gazette No. 60-81536 that a synchronous belt is covered with a woven fabric having woolly yarn of high viscosity polyamide fiber. Also proposed in Patent Application Laying Open Gazette No. 55-40319 is that a heat-resisting synthetic fiber of more than 90% of a strength remaining ratio after 400 hours passed under 120.degree. atomospheric temperature is used as one of weft yarn and warp yarn, a synthetic fiber including nylon 6 or nylon 6,6 is used as the other yarn, and the one yarn exposes more to a surface of the woven fabric than the other yarn and vice versa.
In order to reduce the noise, it is proposed in Utility Model Registration Application Laying Open Gazette No. 62-87238 that at least one ply of a rough woven fabric is embedded in the belt body and at least one ply of surface woven fabric is adhered to the surface of the belt body. Also proposed in Utility Model Registration Application Open Gazette No. 63-11949 that a canvas on which only RFL (resorcin formaldehyde latex) adhesion treatment is provided and in which at least a contact surface with a pulley is uncoated with rubber is used to the synchronous belt.
However, instead of the durability ensured, the noise is not reduced in the former two synchronous belts, and vice versa in the latter two synchronous belts. In other words, both the high durability and the low noise are not obtainable in any synchronous belts.